Early risk of recurrence by subtype of ischemic stroke in population-based incidence studies

Objective: To study the early risk of recurrent stroke by etiologic subtype. Methods: The authors studied risk of recurrent stroke by etiologic subtype (Trial of ORG 10172 in Acute Stroke Treatment [TOAST] classification) in patients in two population-based studies: the Oxford Vascular Study and the Oxfordshire Community Stroke Project. A meta-analysis was performed with data from the only two other published studies reporting equivalent data. Results: The four studies included 1,709 strokes with 30 recurrences at 7 days, 72 at 30 days, and 113 at 3 months. Recurrent stroke risk varied between subtypes (p < 0.001). Compared with other subtypes, patients with stroke due to large-artery atherosclerosis (LAA) had the highest odds of recurrence at 7 days (odds ratio [OR] = 3.3, 95% Cl = 1.5 to 7.0), 30 days (OR = 2.9, 95% Cl = 1.7 to 4.9), and 3 months (OR = 2.9, 95% Cl = 1.9 to 4.5). Odds of recurrence at 30 days for other subtypes were cardioembolic (OR = 1.0, 95% CI = 0.6 to 1.7), undetermined (OR = 1.0, 95% CI = 0.6 to 1.6), and small-vessel stroke (OR = 0.2, 95% CI = 0.1 to 0.6). There was no significant heterogeneity between the studies. Although only 14% of strokes were associated with LAA, this subtype accounted for 37% of recurrences within 7 days. Conclusions: The risk of early recurrent stroke is highest in patients with LAA. This supports the need for urgent carotid imaging and prompt endarterectomy.